A number of experimental and broadcast pre World War II television systems were tested. The first ones were mechanical based (mechanical television) and of very low resolution, sometimes with no sound. Later TV systems were electronic (electronic television).
For a list of mechanical system tests and development, see mechanical television. For a station list see Prewar television stations
During the 1930s there were also experimental transmissions from the Vatican - but further details are unknown. Later Arturo Castellani emerges as the main figure being early regular broadcasts.[20][21][22]